Field of the Invention
Embodiments of the present disclosure generally relate to the field of semiconductor technologies, and particularly, to a photodiode and a method of manufacturing the same, and an X-ray detector and a method of manufacturing the same.
Description of the Related Art
X-ray detection technologies are widely applied in fields such as medical treatment, security, non-destructive inspection, scientific research and the like, and increasingly play important roles in the national economy and the people's livelihood. Currently, film radiography is generally utilized in actual X-ray detection. The X-ray film radiography technology has a high imaging quality, and can correctly provide reliable information about appearance and defects of a test sample. This technology, however, has disadvantages such as complex operation, high running cost, difficulty in saving a result, inconvenience in retrieving the result, poor portability, and damage to eyes of a reviewer due to strong light, and the like.
In order to solve the above, an X-ray digital radiography (DR) detection technology was developed in the late 1990s. An X-ray digital radiography system is provided with a flat panel detector, which has a pixel size that may be less than 0.1 mm, and thus has an imaging quality and a resolution which can be almost comparable with the film radiography technology, while overcoming the defects present in the film radiography technology and providing convenience in computer processing of images. The digital X-ray radiography detection technologies may be classified, according to different electron conversion modes, into a direct conversion type (Direct DR) and an indirect conversion type (Indirect DR).
The direct conversion type X-ray flat panel detector is comprised of a ray receiver, a command processor and a power supply. The ray receiver comprises a scintillation crystal (Gd2O2S or CsI) panel, a large area amorphous silicon sensor array, a readout circuit, and the like. The scintillation crystal panel is used to convert X-ray photons into visible light, and the large-scale integrated amorphous silicon sensor array jointed closely to the scintillation crystal panel is used to convert the visible light from the panel into electrons, which will then be digitalized by the readout circuit and transmitted to a computer so as to form a displayable digital image.
The indirect conversion type detector is comprised of an X-ray conversion layer, an amorphous silicon photodiode, a thin film transistor, basic pixel units for signal storage, signal amplifying and readout circuits, and the like. The indirect conversion type flat panel detector has a configuration mainly comprised of a scintillator (cesium iodide) or phosphor (gadolinium oxysulfide) layer, an amorphous silicon layer functioning as a photodiode and a TFT array. The scintillator or phosphor layer of such flat panel detector can, after being exposed to X-ray, convert the X-ray into an electrical signal, and a charge signal from each pixel is readout by the thin film transistor array and is converted into a digital signal, which will be transmitted to an image processing system of the computer to be integrated into an X-ray image.
The PIN photodiode is a critical component of an indirect conversion type X-ray detection substrate, is a decisive factor for absorption efficiency of the visible light, and has great influences on key indicators such as X-ray dosage, X-ray imaging resolution, image response speed and the like. Processes of manufacturing the PIN photodiode of the indirect conversion type X-ray detection substrate mainly include PECVD (plasma activated chemical vapor deposition) and ion implantation, where PIN devices may be formed conveniently and quickly by using different process gases (for example, SiH4, NH3, N2O, PH3, H2, B2H6, and the like) in the PECVD technology at the same time, the PECVD technology, however, is disadvantageous in that the dosage concentration is constant, doping of a particular region cannot be achieved, and an ion implantation technologies is required to cooperate with the PECVD technology in order to improve performances of the PIN devices.
In view of the above, there is a need to provide a new photodiode and a method of manufacturing the same, and an X-ray detector and a method of manufacturing the same, which can at least partially solve the above problems.